This fall, the U.S. Department of Energy hosted its fifth Solar Decathlon in the District of Columbia's West Potomac Park, a shuttle bus ride from its previous location on the National Mall. University teams from four continents presented a diverse array of solar-powered houses and participated in 10 contests that assessed energy efficiency, livability, appeal, and––new this year––affordability. The less accessible venue, the uncooperative weather, and the premature withdrawal of one team this summer (University of Hawaii, citing timing and financial challenges) did not dampen the students' enthusiasm, the public's interest, or the energy performance of many of the entries. Over the 10-day event, the 19 houses received a total of 357,000 visits and seven projects generated more energy than needed.
Courtesy US Department of Energy, Solar Decathlon
This year's designs ranged from highly conventional to futuristic. Purdue University's house, which placed second overall, staked out one end of this spectrum: With the first garage in the history of the competition, it could fit comfortably into most any U.S. suburb. On the other end was the innovative proposition from The Southern California Institute of Architecture and California Institute of Technology team, which wrapped a wood-framed structure with 16-inch-thick insulation made of recycled blue jeans and an outer skin of vinyl.
China's Tongji University configured shipping containers into a "Y" plan to simplify assembly and transportation while keeping costs down, and Belgium's Ghent University created a two-story house––the only one––that anyone could assemble like a giant Erector Set.
Meanwhile, Ohio State University had fun with translucent white polycarbonate panels, which were spaced apart to visually alternate with a wood substrate on the exterior and extended above a flat roof to screen solar arrays––creating the effect of a flat, crenellated parapet. Additional translucent panels served as operable shades for south- and west-facing windows.
Several entries demonstrated that beauty and solar technology can go hand-in-hand. University of Tennessee elegantly sheathed a simple rectangular box framed by steel tubular trusses, with a sophisticated double-facade of alternating transparent and translucent glass panels. With abundant light and exterior views, and with utility and privacy functions tucked neatly on either end, the interior felt surprisingly expansive.
Another head-turner was the Modernist precast concrete house by Team New Jersey (Rutgers, The State University of New Jersey and New Jersey Institute of Technology). The design included an inverted hip-shaped roof that hid solar and rainwater collection systems plus small openings filled with insulating glass units that playfully perforated massive concrete walls.
And, perhaps in homage to the kiwi bird––a national symbol––the entry from New Zealand's Victoria University of Wellington, which placed third overall, featured an eye-catching winged cedar canopy that optimized electricity generation by permitting air circulation around the photovoltaic (PV) modules it supported.
The Solar Decathlon encourages teams to develop solutions appropriate to their regions. Concerned with the health of the Chesapeake Bay, students from University of Maryland-—whose entry was this year's overall winner—created an ever-present reminder of the occupants' connection to their ecosystem by visually linking the central zone of the house, which includes the bathroom, with exterior vegetation selected to filter and retain water.
North Carolina's Appalachian State University tapped into the state's pioneering history. The home, which won the People's Choice Award, consisted of a main unit plus several outbuildings that could serve multiple auxiliary functions. Shaded by a canopy of bifacial PV panels, the entry deck connects the assemblage and provides additional space for outdoor living while visually celebrating the energy-generating elements.